Functional disorders: rectoanal intussusception.

Rectoanal intussusception (RI) is a telescoping of the rectal wall during defecation. RI is an easily recognizable physiologic phenomenon on defecography. The management, however, is much more controversial. Two predominant hypotheses exist regarding the etiology of RI: RI as a primary disorder, and RI as a secondary phenomenon. The diagnosis may be suspected based on clinical symptoms of obstructive defecation. Diagnostic modalities include defecography as the gold standard. Dynamic pelvic magnetic resonance imaging (DPMRI) and transperineal ultrasound are attractive alternatives to defecography; however, their sensitivity is poor in comparison to the gold standard at this time. Management strategies including conservative measures such as biofeedback and surgical procedures including mucosal proctectomy (Delorme), rectopexy, and stapled transanal rectal resection (STARR) procedures have varied degrees of efficacy.